C Program to find if a string is palindrome or not without built in functions

Program

#include<stdio.h>
void main()
{
	char str[20];
	int i, j, flag;
	printf("Enter a string\n");
	scanf(" %s", str);
	i = 0;
	while(str[i] != '\0')
		i++;
	i--;
	j = 0;
	flag = 1;
	while(str[j] != '\0')
	{
		if(str[j] != str[i])
		{
			flag = 0;
			break;
		}
		j++;
		i--;
	}
	if(flag == 1)
		printf("Entered string is a palindrome\n");
	else
		printf("Entered string is not a palindrome\n");
}

Output 1

Enter a string
gadag
Entered string is a palindrome

Output 2

Enter a string
mysore   
Entered string is not a palindrome